1. Field of the Invention
The present invention relates to encoded remote electrical control systems, and partcularly and to systems for the remote control of power outlets, light fixtures and other devices on a common electrical distribution system.
2. Description of the Prior Art
In a conventional motor vehicle ignition system, a key operated lock is used to actuate the ignition switch. Closure of the switch connects battery power to essential ignition system components such as the ignition coil and the distributor. In the "start" position, battery power also is supplied to the engine's starter. The security of such an ignition system depends on the integrity of the lock, and the degree to which the mechanical installation can prevent tampering or "hot-wiring".
A major weakness in conventional ignition systems is that the wire carrying power from the battery to the ignition coil goes by way of the ignition switch. Direct shorting of the switch contacts is all that is required to start and run the engine. Alternatively, the battery can be directly hot-wired to the ignition system components under the hood. Security is poor.
In the past, the usual approach to improving security has been to enclose the critical interconnections and components in rigid housings. At least one automobile manufacturer locates the ignition coil on the fire wall between the engine and the dashboard, and provides a unitary armored cable from the ignition coil housing to the key switch assembly. Since power must be supplied to the ignition coil to start the engine, "hot-wiring" can only be accomplished by physically destroying the armored cable assembly. While this can be done with the appropriate tools, it is sufficiently difficult so as to discourage a would-be thief who is anxious to accomplish the job quickly.
The difficulty with this prior art approach is that the cost of such armored assemblies is high, and their use complicates normal maintenance. For example, in the system just described if a wire within the ignition coil should break, the entire armored cable assembly must be taken out to permit removal and disassembly of the ignition coil. Replacement ignition coils are only sold as a unit with the armored cable attached.
An object of the present invention is to provide a secure ignition system for a motor vehicle which does not depend on extensive mechanical armoring to prevent theft or "hot-wiring". Another object is to provide a secure ignition system which utilizes an electrical code transmission device, preferably an integrated circuit chip contained in the ignition switch assembly, to transmit an encoded signal to a receiver/decoder associated with the essential ignition system components. Receipt of this signal causes the receiver/decoder to effectuate a necessary electrical connection to the ignition system component, thereby enabling engine operation.
"Hot-wiring" at the ignition switch is prevented since shorting of the leads to the switch and transmitter assembly will not cause transmission of the necessary code, and hence will not result in engine ignition. By enclosing the receiver/decoder and the circuitry used to effectuate the necessary ignition system connection in a small tamperproof housing, "hot-wiring" at the ignition coil or distributor likewise is prevented. The inventive system may be used in conjunction with a pushbutton type electronic combination lock in place of a key-operated lock.
The inventive encoded control systems also are useful for remote control of power outlets, lighting fixtures and other devices in a building electrical system. In a conventional household or office electrical installation, the switches normally are mounted in the walls and permanently wired to associated light fixtures, outlets, and other electrical appliances. Such systems afford little or no flexibility. For example, switches to control overhead lights usually are mounted on the wall next to a door. This is convenient to turn on the lights when entering the room, but may be inconvenient otherwise. For example, in a bedroom it necessitates getting out of bed to turn off the light.
Some flexibility is afforded by providing a pair of single-pole, double-throw switches in separate locations to control the same light or outlet. Typically this is done in a stairway, with switches located at the top and bottom of the stairs. But even with this arrangement, the switch locations are fixed and cannot be moved without major rewiring and structural relocation of the switches in the walls.
A further object of the present invention is to provide an electrical control system in which the switch location is completely flexible. The switches, dimmers and the like are not wall mounted, but are situated in a portable controller or switch box which may be moved to any desired location. Each controlled light fixture, outlet or other device has associated with it a control circuit that responds to an encoded signal transmitted from the controller via the electrical distribution system. When a controller switch is actuated, the transmitted signal is recognized only by the intended control circuit, and effectuates turn-on, turn-off, dimming or other control of the associated electrical device.
With this arrangement, the controller may be plugged into any outlet in the common electrical distribution system. When furniture is moved, the controller also can be moved. Thus in a bedroom, if the bed is relocated, the light switches readily can be positioned next to the new bed location. Alternatively, the controller may be moved from one room to another to remotely control the lights in either of these, or yet another room.